Wealth inequality has deepened over time. The top 3% held 54.4% of all wealth in 2013, up from 44.8% in 1989. The bottom 90% held 24.7% of wealth last year, down from 33.2% in 1989.

The vast majority of Americans own assets of some kind. But ownership rates for most types of assets—stocks and retirement accounts, cars and homes—fell between 2010 and 2013, indicating that "many more families now hold fewer different types of assets," the report said.

Some 65.2% of families owned their primary residence in 2013, the lowest homeownership rate since 1995. The share of families owning a business fell to 11.7%, the lowest level recorded in the survey's 25-year history.

The share of families that own stock continued to decline, though nearly all families in the top 10% owned shares. As a result, they may have benefited the most from the stock market's surge in recent years. "The narrower concentration of wealth gains may explain why wealth effects appear smaller in this cycle than in past cycles," J.P. Morgan Chase economist Michael Feroli said in a note to clients.